Acoustic device



2 Sheets-Sheet l J. D. SEABERT ACOUSTIC DEVICE Filed May 5l, 1930 Nov. 28, 1933.

VENTO? ATTORNEYS N0 28 1933- J. D. SEABERT 1,936,918

ACOUSTIC DEVICE Filed May 31, 1930 2 Sheets-Sheet 2 INVENTOR ATTORNEYS Patented Nov. 28, 1933 1,936,918. vf 1 i ACOUSTIC vJohn D. Seabert, Dayton, iOhio,V asr'signor, rby. l t

mesne assignments, to Radio Corporation, of.,4

"" America, New York, Delaware f.

N. Y., 'a corporation of- ApplieafionMay 31,1930. se'riainousvhoa 19 claims. (c1. 17e-115.5)

This invention relates to an acoustic device and moreV particularly to the mechanical construction and arrangement of parts therein.

An object of this invention is to improve upon the construction and arrangement of extend ing the'leads from the speech coil to the terminal board. n .y y y Another object-ofthis invention is to improve upon the housing of the magnetic frame. This has been accomplished by reinforcing the base of the cup shaped housingmember.V

Another object of this invention is to provide in acoustic device that is cheap, easily constructed and that lends itself to mass production. This has been accomplished Ainter alia-byusing formed metal parts either' riveted or welded together and by reducing the number of parts.

v.Further.objects andadvantages of the present invention will be apparent from the followingA description, lreference being-had tothe accompanying drawings, wherein a preierredembodipresent invention is ment of one form o the clearly shown.

In the drawings: Fig. 1 is a sectional vView or the speechcoil and the diaphragm--showing successive steps of'production drawn'to a'larger scale thanFig.`1. v Fig. 6 is an enlarged .sectional view takenon .the line 6 6 of Figi.

Fig. 7. shows ,a schematic wiring' diagram of the speech coil and a portion of the external circuit.

As best seen in Fig. V1)the reference character Y 1G indicates the field `housing having,v attached thereto, Vas by welding an annular pole piece 12 s and a central pole piece -14 heldin position by Y a. reduced portionpassing through an aperture in the base 16 and through an aperture in the re-y inforcing plate 18. .The reduced portion 15, as shown in the particular modiiication, is riveted to the baseV 16 and the reinforcing plate 18. Instead of riveting the pole, piece-w14 to theframe 10 and the reinforcing plate 18 it could be welded thereto or secured in position by any suitable'fastenin'g` means. l J A magnetic coil 2O provided with terminals 22 and 24, connecting the coil 20to either a source of direct current or Yto a source of rectifiedcurrent forr exciting the magnetic eld circuit, links the center pole piece 14.

The flared edge 32 of a conical shaped dia-v phragm 34 is anchored to a housing 26 by an annulus 30. The housing 26 is spot welded or ofvan acoustic device.:-A 'Figs- 2, 8, 4 and 5 are detail fragmentary viewsz V,le'ads158 and 60 in suitably attached at tothe cup shaped housingzl. Y w Asbest seen in Fig. 6, the conical diaphragm V34 carries a speech coil 36, Wound upon acylindrical support; 38, cemented `togor otherwise sei cured tothe diaphragm 34. Inorder toproperly.

center the cylindrical Support 38vv and the-speech f coil 36 with respectv tothe center pole-piece 14 and the air gap between the pole piece 14 and the annular pole piece 12, aspider 40 is cemented to a` flared portion 42 V of the cylindrical; support 38 and attached to thefcenter pole piece -14by a screw 44.- TheV spider 40 permits` axial moverrientv of ,the speech coil 4and prevents radial .movementthereofs' fisnot incontactfwith' the center pole piece 14, 'as there is provided aclearance between `these members for ythefree the speed coil. f

A spacing member 54 has `been interposed force' thespacing member and', so asxto holdf'the the position'disclosed in Figs. 3,

4and-5.

After this has beenV dvrea'erd, or twine/eatiiat hasbeenknotted at 68 so 'as1 to form the'loop 70,

4is placed betweensthef spacing member 54 and the g ared portion 42. and the inner.- edge. .71 .oi" the diaphragm 34 so as to reinforce all-ofthese parts upon being tied .ory .otherwise secured in;v position,

. preferablyv at azpoint, notshown, diametri'cally opposite from the knot168. y

After the cord 66 has been' securedvin'position the heliXes 72 and 74 are formed'gfromtheleads 58 and 60, integral with the speech'coil 536;. 'each' of these leads receives-eacha branch 76 and 78 of n the bifurcated loop v 70, asbest seen Fig.` 4'.; fThe,

branches 76 and78 may r be pulled into ,position by a suitable hook, similarV to aV crochet hook.l After the branches 76 and 78, which aresubstantially the same'length as the length' of the helixes 72 and 74, have been drawn into position Ythe helixes 72 and 74 are elongated as disclosed in Fig.

` A soft cardboard packing member 48 prevents axialmovementofthe iield 001120'.` Member 48 andunrestrictednmoveinent of 75 'n sfo " Y to reinforce or stiffen the branches nearthe end l -G5isupport for. the helix includes a flexible fibrous vmember cemented to the helix.

The elongation of the helixesA 72 and 74 also Ahasa tendency to wrap theleads 58 and 60 closerand more firmly on the branches'l and '78.

The; portion of the'helix'-72 inv contact with the branch 76 andzthe 'portion' of the helix "le in contact With the branch '78 are now cemented by a Vreinforcing material 80 such'as a good gradeof cement or glue or the like, that has a tendencyv attached to the speech coil. The cord 6 6 circumscribing the coil support' 38 is alsocementedin vposition preferably by the sameA cement so 'as to 1.

rigidly hold the parts iniposition and so as to reinforce the entire structure. f

' The helixes '72 and 74 prevent crystallization of the leads 58 and 60 due to one end being secured at 82 or any other suitable terminalboard andY the other end vibrating with the speech coil. It caribe.` readily seen thatthis'is a vstructureeasily constructed, requiring few parts, eliminating the pigtails now .used in the construction of 'acoustic devices,l eliminating Athe soldering of the pigtail to its lead and at the same time producing a reliable structure which will stand up unfder hard use and abuse.

I Whileitle form of embodiment of the present vinvention as herein disclosed, constitutes a preferred form, it `is'to bel understood that other formsv might be adopted, all coming Within th scope of the claims Which follow.

' `Wha`t is claimed-is as follows: 1

1..An acoustic device comprising an electromagnet,. a diaphragm, a support for said dia- "phragm, a speech coil, a speech coil supporting member,said member holding the diaphragm and vthe speech coil in a relative-fixed position, Va flexible support carried by; saidmember and areinforcing member cooperating With the flexible supi port in supportingthe terminals .of `the speech Coil. y

Y2.*.An acoustic'device lcomprisingia magnetic field, a sound responsive diaphragm, a speech coil, a supportingmemberfor said speech coil said supporting member being iixedly attached to:Y said diaphragm, a support for the terminals of said speech coil. said terminals .being formed into a helix-adjacent to the-supporting member, said suppcrtengaging partY of the helix so as to sup- .Y port the endofthe helix adjacent tothe speech coil, the other end of the helix being free to move thereby .preventing Afailure of the -terminals caused .by the vibration of the speech coil.v V

. 3. In an acousticV device, a speech coil havinga terminal formed into a helix near the speech'co'il, a support for the ,end ofthe helix adjacent-to the speech coil,"said supportpermitting the other end of the helix to flex,^the helical'portionY absorbing ethezvibrations of the coil so as to prevent breakage. of the terminals.

I14a-A devicev according toclaim 3 in which the support for the helix includes a exible cord passing intov the end of the helix.

j 5. VA device according to claim 3 Vinvvhich the fA device according to claim 3 which the supportfor 'the helix includes a flexible loopl 'passing into 'the end of the helix. y

' member.

helix upon movement of e .5, so that substantially only half of each helix vis supported by each a vbranch 76 or 78.

'each helix, said support engaging one end of ,each of the helixes so rthat Vthe Vopposite end is freeto' flex, the helical-portionl absorbing jthe vibrations. of thevv speech coil so as to prevent 'breakage of4 the terminals.

:10. A device according to claim 9. in which said support includes a bifurcated member, eachy branch of -said bifurcated member engaging a helix. y

11. A device according to claim 9 in which said 'support includes a bifurcatedmember, each branch of said bifurcated rmember passing into a helix.

12. A device according V to claim vil in which said support includes a branched loop, each; i

branch of said loop passing finto 'a helix.'-v

13. A device according to claim 9` in which said support includes a bifurcatedilexible member and a reinforcing .means for 'said flexible member.V

14. A device accordingto claim Qin which said supportincludes a branched flexible loo-p,

each vbranch of said loop passing into a helix,

and a `reinforcing member for said bifurcated l5. Adeviceaccording jtoclaim 9 in which fno f said support includes a bifurcated loop,-ea'ch' branch of said loop engagingV a'helix'and a rep inforcing Vmember for cementing said branches to'said helix. ldvn-an vacoustic device,

a speech coil having' a pair of terminals, each of saidterminals beingV` formed intoa helix adjacent tc the'speech coil, a cylindrical member for supporting said speech coil, and a support forthe helixes,`Y said support fixing one endofeach 'of saidhelixes to said cylindrical member' so 1that the vibrations of the 'movable collare absorbed by saidhelixes" so as 4to prevent breakage of said leads. l

. 17. Avdevice according to claim 16 in which saidsupport includes afbranched loop carried `by said cylindrical member, each of fthe' branches of said loop engaging an end ofsai'd helixes.

"18.'In' anacoustic device, a speech'coil having a terminal lead, said lead being formed-into a helix at or near the speech cod-flexible means attached-to the coil -t supportthe adjacent end of said helix,; and means securingy one vend ofthe helix totheflexible means so as to localize ilexing of the leadin theremote portion ofthe said helix. Y

.19. In an'electric'al apparatus having a movable coil, and a support for said coil, theV ,combination comprising, a terminal lead joining the coil and carried by the support,"said leadbeing` formed into a helix, flexible means carried by Y the support and engaging part ofthe helix so as to support it from one end,'and means for localizing flexing of the lead in the remote'endof the said coil.` f JOHN veD. SEABERT.

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